Cerro Castillo is named for what it looks like: a rank of black basalt turrets standing at 2,675 metres over the Aysén region of Chilean Patagonia. A hanging glacier holds on beneath the summit wall, and what melts off it drops into a lagoon at the foot of the rock. Getting all three into one view costs you six or seven hard hours up from the road, through southern beech forest and then loose scree, to a mirador above the water, where the towers and the ice stand again on the surface below. That is the day walk, and it is what most people come for. Four days buys you the other version, a fifty-kilometre circuit from Las Horquetas over the passes, camping past hanging glaciers and mountain lagoons that the day-walkers never reach. In April the lenga forest along the Río Ibáñez turns deep red and gold under the grey rock.
The valleys below are worked as well as walked. Patagonian stock riders still move cattle through them, and they take you along the lower trails on horseback, which covers ground quietly enough that guanaco and birds stay where they are. Three kilometres from the village of Villa Cerro Castillo, a tall rock face called the Paredón de las Manos is stencilled with dozens of human hands. Hunters pressed their palms to the stone and blew red pigment around them between three and six thousand years ago, long before any road reached this valley. The rarest thing here is harder to see. Fewer than 1,500 huemul are left in the wild, the Andean deer on Chile's coat of arms, and these valleys hold one of the largest surviving groups. They split by ground: ones and twos on the rocky slopes, larger mixed groups out on the open valley floor. Early on the lower trails you watch the treeline rather than the path ahead, and the condors are working the wind above the towers at the same hour.